Evaluación de la patogenicidad en ratas del Paecilomyces lilacinus LPL-01 utilizando vías diferentes de exposición / Pathogenicity evaluation of Paecilomyces lilacinus to rats

Los nemátodos parásitos de las plantas, conocidos como plagas agrícolas desde el siglo XIX, causan un 9% de pérdidas de cultivos en los países desarrollados y un 14% en los países en desarrollo. El Paecilomyces lilacinus es un hongo parásito que ataca formas sedentarias de los nemátodos, como los huevos. Su valoración como agente microbiano de control debe incluir una evaluación de su virulencia hacia organismos no-diana, tomando en consideración las vías posibles de exposición de los humanos. Para evaluar la patogenicidad de la cepa LPL-01 del P. lilacinus en ratas, se administró por las vías oral, pulmonar e intravenosa. Las observaciones clínicas fueron diarias, y se evaluó el comportamiento del peso corporal. Se estimó el aclaramiento mediante recolección de las heces fecales y análisis de muestras de los pulmones y de la sangre, según la vía de administración, y se evaluó la infectividad mediante toma de muestras de órganos de animales inoculados sacrificados a intervalos. Durante estos sacrificios, y al final de los ensayos, se realizó la necropsia de los animales. No ocurrieron mortalidades, ni evidencias de patogenicidad relacionada con el tratamiento en los ensayos oral y pulmonar, no provocando el hongo una infestación significativa. Por vía endovenosa, el microorganismo provocó alteraciones anátomo-patológicas en hígado y bazo, coincidiendo con el período de máxima infestación. Se concluyó que la cepa LPL-01 del P. lilacinus, a las dosis evaluadas, no es patogénica por las vías oral y pulmonar, siendo levemente patogénica por vía endovenosa

Plant parasitic nematodes have been recognized as agricultural pests in Europe as early as the late 19th century. It has been estimated that plant parasitic nematodes cause crop yield losses of nearly 9% in the developed world, and over 14% in developing countries. The Paecilomyces lilacinus is a parasitic fungi attacking sedentary stages of nematodes, e.g. eggs. Evaluation of this fungus as a microbial control agent, must include an evaluation of its virulence towards non-target organisms, especially vertebrates, with consideration given to potential human exposure scenarios. With the aim of assessing the pathogenicity in rats of the strain LPL-01 of Paecilomyces lilacinus, this fungus was given using several routes of exposure (oral, pulmonary and intravenous route). In all of the assays, clinical examinations were performed daily after administration, and body weight gain of animals was evaluated. Clearance was estimated by means of collection of feces and examination of lungs and blood, depending on the route used, and ineffectiveness was evaluated by enumerating microorganisms from organs and corporal fluids in animals sacrifice at intervals. A gross necropsy of all animals was performed at interim or final sacrifice. There were no mortalities, and no evidence of pathogenicity or treatment-related toxicity either in oral or pulmonary toxicity/pathogenicity tests, without significant infection of test animals. In the intravenous toxicity/pathogenicity test, P. lilacinus caused anatomopathological changes in liver and spleen at the same period when higher infectivity was achieved. It was concluded that P. lilacinus is not pathogenic by oral and pulmonary route, but has some pathogenic effects when intravenous injection is performed

Failure of exogenous LH to prevent PGF2alpha-induced luteolysis in beef cows.

Henderson and McNatty (Prostaglandins 9:779, 1975) proposed that LH from the preovulatory LH surge attached to receptors on luteal cells and that this attachment might protect the early corpus luteum from PGF2alpha induced luteolysis. To test this hypothesis, experiments were performed on heifers at day 10-12 of the cycle. Both jugular veins were catheterized and infusions of either saline (0.64 ml/min) or LH-NIH-B9 (10 microgram/min; 0.64 ml/min) were given. Saline infusions were from 0-12 h; LH infusions were for 10 h and were preceded by a 2 h saline infusion. All animals were given 25 mg PGF2alpha im at 6 h (6 h into the saline infusion and 4 h into the LH infusion). Blood samples were taken at 0.5 h, 1 h and 4 h intervals from 0-12h, 13-18 h and 12-42 h respectively. Serum was assayed for LH and progesterone by radioimmunoassay methods. Two animals received saline and two received LH in each experiment. Each treatment was replicated 6 times. LH infusion resulted in a mean serum LH of 75 ng/ml compared to 0.90 ng/ml in saline infused animals. This elevation of LH did not alter PGF2alpha induced luteolysis as indicated by decline in serum progesterone. This experiment does not support the hypothesis that the newly formed corpus luteum is resistant to PGF2alpha because of protection afforded by the proestrus LH surge.